Pressure transmitter is an instrument which measures the pressure and convert it with an electrical or pneumatic signal. Pressure transmitter is one of the Instrumentation’s most frequently-used instruments for controlling and monitoring various industrial processes.
They are positioned on pipes and tanks; essentially everywhere in the process that measuring is required. Transmitters consist of three main parts; amplifier, transducer and sensor. There are two types of pressure transmitters; electrical and pneumatic. Electrical pressure transmitters have an output between 4 to 20 ma whereas, pneumatic transmitters have an output between 3 to 15 psi which can change according to the changes in the input physical quantity.
It is worth noting that for all types of transmitters, transducer and amplifier are identical and only the sensor part varies depending on different physical quantity . For instance, in pressure transmitters, the sensor is sensitive to pressure rate and in temperature transmitters, the sensor is sensitive to temperature rate.
Pressure transmitters use various mechanisms in order to measure pressure accurately. The performance of the sensor part is different in different types of transmitters. For instance, diaphragm sensors perform in a way much like a capacitor. In these sensors, by applying the pressure on transmitter’s diaphragm, the gap between capacitor sheets changes and ultimately electrical capacity changes. As capacitor’s capacity changes, electrical signal changes accordingly and subsequently, the amount of pressure for the intended physical quantity can be measured. The material used for these sheets should be chosenaccording to the physical and chemical characteristics [such as temperature, corrosion] of the fluid which is to be measured.
These instruments come in various models depending on the application and measurement’s range. Moreover, Smart versions with Hart, Fieldbus and Profibus protocols are available and they offer higher precision and more options.
This company offers pressure transmitters with Brazilian brand “Smar” and American brand “Kleev”.